Cancer risk elevated with severe gum disease

(Reuters Health) - People with severe gum disease may be at greater risk for cancer, a U.S. study suggests.

“What this report does is continue the support of the idea that gum disease is not just a matter of what happens to our teeth,” said Dr. Leonard Lichtenfeld, deputy chief medical officer for the American Cancer Society.

Researchers performed dental exams on 7,466 individuals from Mississippi, Maryland, Minnesota and North Carolina and then monitored them for an average of 15 years. None of the participants had cancer at the start of the study.

Fifteen years later, individuals with severe gum disease on the dental exam had a 24 percent higher risk of developing any kind of cancer, and more than double the risk of lung cancer, compared to those with no or mild gum disease.

These findings, based on actual dental exams, are consistent with prior studies that have used self-reports of gum disease, lead study author Dominique Michaud, professor of public health and community medicine at the Tuft’s School of Medicine, told Reuters Health.

The researchers took cancer risk factors into account, including age, gender, weight status, smoking, race and socioeconomic status. In the study, being older, male, black, less educated, obese or a smoker was more common with advancing periodontitis severity. Overall, researchers did not see links between periodontal disease and breast cancer, prostate cancer or blood or lymphatic-related cancers.

Nearly half all Americans over age 30 suffer from some form of gum disease, according to the Centers for Disease Control and Prevention (CDC). Also known as periodontal disease, the condition develops when bacteria in the mouth infect tissue surrounding the tooth, causing inflammation - which has long been associated with cancer risk. Unchecked, gum disease can progress to tooth loss.

In the study, associations between gum disease and cancer were generally weaker, or not apparent among black participants, except for lung and colorectal cancers, the authors report in the Journal of the National Cancer Institute.

“We don’t have an answer for the differences we observed by race,” Michaud said in an email.

Lichtenfeld, who was not involved in the study, said this could be due to additional barriers black Americans might face compared to their white counterparts.

“There are issues for black Americans such as access to care, education and socioeconomic status. Although some of those factors were controlled (in the study), others were not, and that may make a sufficient difference such that periodontal disease may not be a distinguishing characteristic among black Americans the same way it is among white Americans.”

The study can’t prove that gum disease actually causes cancer. Furthermore, given that the dental exam predated the diagnosis of cancer, any faulty measurement of periodontal disease could produce an under- or over-estimation of the correlation. Despite adjusting for smoking dose and duration in participants, the authors also said they could not rule out confounding by smoking, especially for lung cancer.

In an email to Reuters Health, the American Dental Association highlighted some factors that may have also influenced the findings: “Both income and health insurance are very influential predictors of whether someone can access timely and high quality dental or health care, and both income and health insurance patterns relate to race in the United States.”

SOURCE: http://bit.ly/2EpgjjF Journal of the National Cancer Institute, online January 12, 2018.